• Restorative Dentistry and Endodontics
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• v.33 no.6
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• pp.499-506
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• 2008

The purpose of this study was to compare the push-out strength of a fiber post cemented with various resin cements. Newly extracted 36 human mandibular premolars which had single root canal were selected and their crown portions were removed. The root canal was instrumented using $PROTAPER^{TM}$ system and obturated using continuous wave technique. In each root, a 9-mm deep post space was prepared. #2 translucent fiber post (DT Light post, Bisco Inc., Schaumburg, IL, U.S.A.) was cemented using injection technique with Uni-dose needle tip (Bisco) and six different resin cements. The tested resin cements were Duo-Link (Bisco Inc., Schaumburg, IL, U.S.A.), Variolink II (Ivoclar-Vivadent AG, Schann, Liechtenstein), Panavia F (Kuraray Medical Inc., Okayama, Japan), Multilink Automix (Ivoclar-Vivadent AG, Schann, Liechtenstein), RelyX Unicem (3M ESPE Dental Products, St. Paul, MN, U.S.A.), and Maxcem (Kerr Co., CA, U.S.A.). After storage in distilled water for 24 hours, each root was transversally sectioned into approximately 1-mm thick sections. This procedure resulted in 6 serial sections per root. Push-out test wasperformed using a universal testing machine (EZ Test, Shimadzu Co.) with a crosshead speed of 1 mm/min. The data were analyzed with one-way ANOVA and Tukey HSD (p=0.05). The push-out strength of the groups which cemented fiber post with Panavia F and Multilink Automix were lower than those of the other groups. But, there were no statistically significant difference among groups at a probability level of 0.05.

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.57-72
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• 1998

This study has been carried out to investigate the effects of Ukgansan(UGS) extract on anti-convulsive, antipyretic, analgesic, sedative and GABAergic system of experimental animals. The results of this study were as follows : 1. UGS extract prolonged significantly the beginning time to convulsion and death induced by strychnine. 2. UGS extract prolonged significantly the time to death induced by electrical shock of ECT unit.(3 sec, 200 F, 25 mA) 3. On the experiment of hypothermic effects of UGS extract on the rectal temperature of mouse, UGS extract decreased significantly the rectal temperature of mouse 4. On the experiment of antipyretic effects of UGS extract on the febrile induced by the subcutaneous injection of $150\;{\mu}g/kg$ endotoxin in mouse, UGS extract decreased significantly the rectal temperature of mouse. 5. On the experiment of analgesic effects of UGS extract on the writhing syndrome induced by intraperitoneal injection 0.7% acetic acid 1 ml/100g in mouse, the writhing syndrome induced by acetic acid was reduced significantly by administration of UGS extract. 6. On the experiment of effects of UGS extract on spontaneous motor activity measured by wheel cage method in mice, the spontaneous motor activity was reduced significantly by administration of UGS extract. 7. On the experiment of effects of UGS extract on the activity of GABA-transaminase(GABA-T) in mouse brains after 21 days of oral administration of UGS extract. the activity of GABA-T was reduced significantly by administration of UGS extract. 8. On the experiment of effects of UGS extract on the activity concentration of GABA in mouse brain after 21 days of oral administration of UGS extract, the activity concentration of GABA was reduced significantly by administration of UGS extract. 9 On the experiment of effect of UGS water extract on the activity of GAD in mouse brain after 21 days of oral administration of UGS extract, the activity of GAD was reduced significantly by administration of UGS extract. According to the these results, Ukgansan extracts reveal the effects on the anti-convulsive, antipyretic, analgesic, sedative and GABAergic system.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.377-381
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• 2005

We tried to extract bone morphogenetic protein (BMP) from the freeze-dried bovine cortical bone (FBCB) for bone graft, which were defatted with chloroform-methanol for 20 days, freeze-dried at $-80^{\circ}C$ for 7 days and sterilized by ethylene oxide gas. Two kg of FBCB were pulverized in a wheel mill to $0.5-2.0mm^3$ cubic in size. The bone particles were demineralized in 0.6N HCI for 10 days at chloroform-methanol$4^{\circ}C$ and defatted with chloroform-methanol for 6 hours at room temperature, which was going to be defatting and demineralized cortical bone (DDM). For extracting BMP, DDM was agitated continuously through 72 hours with magnetic stirrer at $4^{\circ}C$ into 12 times of volume of 6 M guanidine hydrochloride (Gdn-HCl) solution containing proteinase inhibitors to protect BMP such as 2mM N-ethylaleimide, 1mM iodoacetic acid, 1mM phenylmethylsulfonyl fluoride and a sterilizer, 1mM sodium azide. The extraction procedure was repeated for three times. All extracted solution was centrifuged at 10,000 rpm for 30 min and then, the supernatant was dialyzed with 12 times of volume of deionized water at $4^{\circ}C$ for 24-72 hours, which cut off below 6,000-8,000 molecular weight. The dialyzed specimen contained crude-BMP was centrifuged, freeze-dried, and weighted. Through these processing, we could obtained $84.9\%$ as FBCB, $17.8\%$ as DDM and $0.71\%$ as crude-BMP from the wet cortical bone without cancellous bone, marrow and muscles. The crude-BMP were obtained $68.3\%$ from the first extraction, $29.6\%$ from secondary and $2.1\%$ from tertiary, respectively. It was suggested that high yield of crude-BMP migth be explained by three-time repetition of the extraction processing for crude-BMP with Gdn-Hcl sol.

• Restorative Dentistry and Endodontics
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• v.26 no.1
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• pp.16-22
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• 2001

The purpose of this study was to evaluate the marginal microleakage of condensable composite resin restorations according to flowable resin lining of internal cavity wall. The eighty extracted human molar teeth without caries and/or restorations are used The experimental teeth were randomly assigned into four groups of ten teeth each. Eighty caries-free extracted human molars were used in this study. The conventional class II cavities (box-shaped on mesial and distal surface, faciolingual width : 3mm, gingival wall depth : 1.5mm) were prepared 1mm below cementoenamel junction with a # 701 carbide bur. The teeth were divided into four groups, and then each group were subdivided into A & B group according to flowable resin & compomer lining ; Group 1-A : Tetric Ceram filling, Group 1-B : Tetric Flow lining and Tetric Ceram filling, Group 2-A Ariston pHc filling, Group 2-B : Tetric Flow lining and Ariston pHc filing, Group 3-A SureFil filling, Group 3-B : Dyract Flow lining and SureFil filling, Group 4-A : Pyramid filling, Group 4-B : Aeliteflo lining and Pyramid filling. To simulate as closely as possible the clinical situation during retoration placement, a "restoration template" was fabricated, and the condensable resin was filled using a three-sited light-curing incremental technique. All the materials used were applied according to the manufacturers' instructions. The specimens were stored in the 100% humidity for 7 days prior to thermocycling (100 thermal cycles of 5~55$^{\circ}C$ water with a 30-second dwell time) The specimens were immersed in 2% metyleneblue dye for 24 hours, and then embedded in transparent acrylic resin and sectioned mesiodistally with diamond wheel saw. The degree of marginal leakage was scored under stereomicroscope ($\times$20) and the data were analyzed by Kruskal-Wallis test and Wilcoxon signed ranks test. The results were as follows : 1. In the gingival margins of all the group, microleakage of subgroup B was less than subgroup A. 2. In the group 1, 2, 4, there was significant differences between subgroup A and B (p<0.05), but in the group 3, there was not significant different between group 3-A (SureFil) and group 3-B (Dyract flow/SureFil) (p>0.05). 3. In the subgroup A and B, there was significant different between all group except group 4 of subgroup A. From the results above, it was suggested that the cavity lining of flowable resin and flowable compomer in condensable resin restoration decrease microleakage at gingival margin, and does improve their ability to seal the gingival margin of class II preparation.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.381-391
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• 1999

A new 5th generation adhesive system(ONE-STEP) has been supplied which operators can apply to conditioned tooth surfaces by one simplified step. The purpose of this study was to determine whether different methods of adhesive application and various air drying duration after applying adhesive affect the shear bond strength of composite resin to dentin, and to evaluate the adhesive pattern of composite resin and dentin under SEM. Seventy-seven extracted human molar teeth were cleaned and mounted in palstic test tubes. The occlusal dentin surfaces were exposed with Diamond Wheel Saw and smoothed with Lapping and Polishing Machine (South Bay Technology Co., U.S.A.). Teeth were randomly divided into 7 groups (n=11), In experimental A group, adhesive was applied to dentin with agitation for 20 sec. In experimental N-A group, adhesive were continuously applied to dentin for 20 sec. Also control and experimental 1, 2, 3, 4 groups were dried for 10, 0, 5, 20, 30 seconds after applying adhesive, respectively, Adhesives were light cured for 10 sec. A gelatin capsule 5mm in diameter was filled with Aelitefil$^{TM}$ composite resin, placed on the treated dentin surface and light cured for 40 see, from three sides, All specimens were stored in distilled water at room temperature for 24 hours. The shear bond strengths were measured using a universal testing machine(AGS-1000 4D, Japan) at a crosshead speed of 5mm/min. An one-way ANOVA and LSD test were used for statistical analysis of the data. For SEM evaluation, seven specimens were made and sectioned. Representive postfracture and seven specimens were mounted on brass stubs, sputter-coated with gold and observed under SEM. The results were as follows : 1. The shear bond strength of experimental A group which adhesive were applied to dentin with agitation was higher than that of experimental N-A group (continuous application), and there was significant difference between two groups (p<0.01). 2. The interface between composite and dentin according to different application methods showed close adaptation in experimental A group and showed tinny gap in experimental N-A group. 3. The shear bond strength accoding to various air drying duration was the lowest value(7.57${\pm}$2.60 MPa) in experimental 1 group, so there was significant difference between experimental 1 group and other four groups (p<0.05). But there was no significant difference of shear bond strength between four groups (p>0.05). 4. The interface between composite and dentin according to various air drying duration showed close adaptation in control group and tinny gap in experimental 3 and 4 groups. But experimental 1 and 2 groups showed $30{\mu}$ and 6 - $10{\mu}m$ thick gaps, respectively.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.103-112
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• 2009

The purpose of this study was to compare the effect of curing methods of adhesive resins and resin cements in the root canal. Crown portions of 32 single-rooted mandibular premolars were removed. Routine endodontic treatment was done, and 9 mm deep post spaces were prepared within root canals. No.3 FRC Postec posts (Ivoclar-Vivadent AG, Liechtensteih) were cemented in the post spaces by self-(SC) or light-curing (LC) using two dual-cured adhesives (Adper Scotchbond multi-purpose plus and Exite DSC )and resin cements (RelyX ARC and Variolink II). They were assigned to 4 groups (n=8): R-SC, R-LC, V-SC, V-LC group. After stored in distilled water for 24 hours, each root was transversally sectioned with 1.5 mm thick and made three slices. The specimens were subjected to push-out test in a universal testing machine (EZ Test, Shimadzu Co., Japan) with a crosshead speed of 1 mm/min. The data were analyzed with repeated ANOVA and one-way ANOVA. Also the interface of post-resin cement and resin cement-canal wall of each group was observed under FE-SEM. When fiber posts were cemented into the root canal using total-etch adhesives, the bond strength and adaptation between post and root canal dentin was affected by curing method. Self-cure of adhesives and resin cements showed higher bond strength and closer adaptation than light-cure of them.

• The Journal of Internal Korean Medicine
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• v.18 no.2
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• pp.65-82
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• 1997

This study has been carried out to investigate the effects of Cheonmagudeungyeum(CGY) extract on anti-convulsive, antipyretic, analgesic, sedative and GABAergic system of experimental animals. The results of this study were as follows : 1. CGY extract prolonged significantly the beginning time to convulsion and death induced by strychnine. 2. CGY extract prolonged significantly the time to death induced by electrical shock of ECT unit(3 sec, 200 F, 25 mA) 3. On the experiment of hypothermic effects of CGY extract on the rectal temperature of mice, CGY extract decreased the rectal temperature of mice. 4. On the experiment of antipyretic effects of CGY extract on the febrile induced by the subcutaneous injection of $150\;{\mu}g/kg$ endotoxin in mice, CGY extract decreased significantly the rectal temperature of mice. 5. On the experiment of analgesic effects of CGY extract on the writhing syndrome induced by intraperitoneal injection 0.7% acetic acid 1 ml/100g in mice, the writhing syndrome induced by acetic acid was reduced significantly by administration of CGY extract. 6. On the experiment of effects of CGY extract on spontaneous motor activity measured by wheel cage method in mice, the spontaneous motor activity was reduced significantly by administration of CGY extract 7. On the experiment of effects of CGY extract on the activity of GABA - transaminase (GABA-T) in mouse brains after 21 days of oral administration of CGY extract, the activity of GABA-T was reduced significantly by administration of CGY extract. 8. On the experiment of effects of CGY extract on the activity concentration of GABA in mouse brain after 21 days of oral administration of CGY extract, the activity concentration of GABA was reduced significantly by administration of CGY extract. 9. On the experiment of effect of CGY water extract on the activity of GAD in mouse brain after 21 days of oral administration of CGY extract, the activity of GAD was reduced significantly by administration of CGY extract. According to the these results, Cheonmagudeungyeum extracts reveal the effects on the anti-convulsive, antipyretic, analgesic, sedative and GABAergic system.

• Journal of Drive and Control
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• v.17 no.4
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• pp.133-140
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• 2020

Traction performance of a tractor varies depending on soil conditions. Sinkage and slip of the driving wheel for tractor frequently occur in a reclaimed land. The objective of this study was to develop a tractor suitable for a reclaimed land. Traction performance was evaluated according to soil conditions of reclaimed land and paddy field. Field experiments were conducted at two test sites (Fields A: paddy field; and Field B: reclaimed land). The tractor load measurement system was composed of an axle rotation speed sensor, a torque meter, a six-component load cell, GPS, and a DAQ (Data Acquisition System). Soil properties including soil texture, water content, cone index, and electrical conductivity (EC) were measured. Referring to previous researches, the tractor traveling speed was set to B3 (7.05 km/h), which was frequently used in ridge plow tillage. Soil moisture contents were 33.2% and 48.6% in fields A and B, respectively. Cone index was 2.1 times higher in field A than in field B. When working in the reclaimed land, slip ratios were about 10.5% and 33.1% for fields A and B, respectively. The engine load was used almost 100% of all tractors under the two field conditions. Traction powers were 31.9 kW and 24.2 kW for fields A and B, respectively. Tractive efficiencies were 83.3% and 54.4% for fields A and B, respectively. As soil moisture increased by 16.4%, the tractive efficiency was lowered by about 28.9%. Traction performance of tractor was significantly different according to soil conditions of fields A and B. Therefore, it is necessary to improve the traction performance of tractor for smooth operations in all soil conditions including a reclaimed land by reflecting data of this study.

• The Korean Journal of Ecology
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• v.17 no.3
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• pp.355-366
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• 1994

The purpose of this study was to investigate the changes of water quality and the patterns of self-purification with season in Gokneung stream. The vegetation in the ecosystem around Gokneung stream was dominated by Quercus species. In the physicochemical analysis based on the contents of DO, BOD, conductivity and total phosphorus, the upstream seemed to have been polluted, but the downstream was self-purified. In biological investigation by bentic macroinvertebrates, the result was similar to that in the physicochemical analysis. The self-purification constant based on BOD of the upstream, 1.013, was the highest. In the self-purification constants with month, that of September was 0.995 and that of January was 0.272. These results indicated that the self purification capacities of spring and autumn were larger than those of winter and summer in Gokneung stream.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.97-109
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• 2009

One of the main causes of asphalt rutting is high temperature of the pavement. Nevertheless, there has been few research on lowering the pavement temperature for reducing rutting. This study investigated the performance characteristics of moisture-retaining porous asphalt pavement, which is known to have a temperature reducing effect. The purpose of this study is to quantify the temperature reducing effect of moisture-retaining porous asphalt pavement and its effect of reducing rutting through Accelerated Pavement Testing(APT). Additionally, the possibility of reducing the thickness of the pavement in comparison to general dense grade pavement by analyzing structural layer coefficient of moisture retaining pavement. A total of three test sections consisting of two moisture-retaining porous asphalt pavement sections and one general dense-grade porous asphalt pavement section were constructed for this study. Heating and spraying of water were carried out in a regular cycle. The loading condition was 8.2 ton of wheel load, the tire pressure of $7.03kgf/cm^2$, and the contact area of $610cm^2$. The result of this experiment revealed that the temperature reducing effect of the pavement was about $6.6{\sim}7.9^{\circ}C$(average of $7.4^{\circ}C$) for the middle layer and $7.9{\sim}9.8^{\circ}C$(average of $8.8^{\circ}C$) for surface course, resulting in a rutting reduction of 26% at the pavement surface. Additionally, the structural layer coefficient of moisture retaining pavement measured from a laboratory test was 0.173, about 1.2 times that of general dense grade pavement. The general dense-grade porous asphalt pavement test section exhibited rutting at all layers of surface course, middle layer, and base layer, while the test sections of moisture-retaining porous asphalt pavement manifested rutting mostly at surface course only.